DE3504514A1 - Method and device for the exhaust gas catalysis of diesel engines - Google Patents

Abstract

Method and device for the exhaust after burning of diesel engine exhaust gases in catalytic converter packings, lying eccentrically in relation to one another, for the adsorption of soot particles, especially in the starting phase and after burning catalytic converter honeycomb for the after burning and nitrogen oxide reduction in the power phase of the engine. By virtue of the flow ducting, the after- burning device is also suitable as a silencer.

Description

Method and device for exhaust gas catalysis of diesel engines

gates The invention relates to an exhaust gas catalytic converter for diesel engines the unburned parts, especially soot and unburned hydrocarbons used as a reducing agent for nitrogen oxide reduction. The unburned components with the excess oxygen in the exhaust gas and the oxygen in the nitrogen oxides burned and so rendered harmless.

Soot filters have been proposed for diesel engines so far, the unburned Substances stored in the wall surface of ceramic bodies and then at Burned reaching the combustion temperatures. The combustion temperature was partially reduced by the introduction of catalysts.

These filters have a large volume in order to reduce the pressure loss of the Not to let the exhaust pipe get too big.

In addition, oil ash residues remain in the filter walls Burning off will no longer be yellowed out and so the pressure loss of the filter is continuous raise. Eventually the walls crack and the Filters.

The disadvantages tried to circumvent an invention P 40 682 by an exhaust gas catalytic converter was switched into the exhaust gas flow of a diesel engine, the to accomplish the combustion of the unburned components. Particular difficulties prepares in this invention the abundant foot in the starting process the phase has not yet reached the reaction temperature of the catalyst.

The present invention now has the advantages of both Systems come into their own and both soot storage when starting the Diesel engine as well as soot combustion during the load phase with nitrogen oxide reduction to be made possible without excessive pressure losses being able to build up. In particular the invention is not intended to allow any increase in pressure loss during operation.

According to the invention, this is done by combining a packing and a honeycomb catalyst in such a way that the exhaust gas first in a packed catalyst from the soot particles are freed and then in a honeycomb catalytic converter for reduction the nitrogen oxides and for post-combustion is further purified.

The packed catalyst is designed so that when it increases the pressure loss the bed can expand, so that a stronger accumulation of soot in the cold start phase does not lead to a significant increase in the pressure loss can lead. Furthermore, the free flow cross-sections are designed so that Given the size of the device, there is a minimum of pressure loss.

According to the invention this is solved so that after leaving the exhaust gas from the engine, this is introduced into an annular chamber, in which at the lower end a FiJtllko'rkatlysator- and - + filter is located. The annular chamber is eccentric formed, so that there is a particularly large flow cross-section in the filler body and thus forms a lower pressure loss.

To transfer to the honeycomb catalytic converter, a Boundary perforated plate installed, which the filler particles on leaving the filler bed hinders.

After the perforated plate, the exhaust gas begins to be transferred into the catalytic converter honeycomb. In total, the exhaust gas flows through the annular chamber and passes by about 270 degrees thereby the catalytic packing and is then deflected by 180 degrees, so that Overall, a vertical flow to the device and a horizontal transfer the exhaust gases are produced.

Overall, this results in a space-saving product implementation option.

The following is the device of the method according to the invention described. It is explained with reference to FIGS. 1 and 2.

The device consists of an exhaust nozzle 1 tangentially in the device is inserted. This ends in the eccentric annular space 2, the is fluidically connected to the inlet nozzle.

In the annulus is the FiJillkdrperschi & Ltung 7 die consists of catalytically coated filling bodies, for example spheres.

At the end of the ball bed there is the perforated closing plate 4, which prevents the discharge of the packing into the uspuff.

The transfer of the exhaust gas into the catalyst chamber takes place in the transition part of the annular space 5. This is followed by the catalyst chamber 6, in which the catalyst 7 in the embedding 8 and the catalyst holder treatment 9 is embedded in the catalyst, the gas collection chamber 10 closes with the Exhaust pipe 11.

Surprisingly, it has now been found that the inventive Device not only represents the optimum in space utilization, but also causes particularly intensive sound insulation. This can be part of the caused Pressure loss can be compensated for by saving the silencer Two exemplary embodiments of the method and the device will now be described in more detail below characterize.

A 1 6 1 diesel engine consumes 7 kg of diesel oil per hour. He will operated with an air ratio of 1.36. The honeycomb catalyst has a diameter of 100 mm and the inlet nozzle has a diameter of 40 mm. The ball dumping height is 4 cm, with a temperature of 600 degrees C and a pressure loss of 0.25 bar results in 80% of the pressure loss from the pressure loss alone the pebble bed.

The description of the device serves as the second exemplary embodiment of the above procedural example.

A tangential inlet pipe with a diameter of 40 mm is on an annular chamber with a diameter of 160 mm is welded on. In the ring chamber if the catalyst holder is approx. 20 mm eccentric, it has a diameter of approx. 120 mm supported.

The catalytic converter is installed in such a way that, in a horizontal arrangement, the largest annular gap width of approx. 42 mm comes to lie down. This will causes the packing, e.g. balls with a diameter of 5 mm, at all times come to rest at the bottom of the annular chamber and the necessary flow cross-sections Leaving it free A ball retainer with holes approx. mm in size is used perforated plate provided, which is installed in a wedge shape so that the flow velocity of the exhaust gas remains constant as it flows through the sheet metal.

The space above the perforated plate closes with an opening of approx. 15 cm to the catalyst chamber, from where the Nbgas flows through the catalyst, enters the gas collection chamber and from there into the exhaust.

Since special attention was paid to the pressure loss in the design some pressure loss examples are listed in Tab. 1 that are based on arithmetic Paths have been determined and relate to the execution described.

By increasing the outer diameter, you can at any time further reduce the pressure losses.

Amount of fuel 7 8 9 10 11 12 13 m (Br) = kg / h 20 0.0311 0.0386 0.0468 0.0554 0.0605 0.0699 0.0859 dumping height 25 0.0317 0.0390 0.0472 0.0560 0.0612 0.0708 0.0868 (mm) 30 0.0327 0.0404 0.0490 0.0582 0.0638 0.0739 0.0906 T = 300 degrees C 35 0.0384 0.0479 0.0585 0.0699 0.0780 0.0908 0.1104 40 0.1656 0.2142 0.2690 0.3296 0.3931 0.4651 0.5495 20 0.0386 0.0474 0.0572 0.0635 0.0739 0.0913 0.1042 dumping height 25 0.0390 0.0479 0.0577 0.0642 0.0747 0.0922 0.1054 (mm) 30 0.0402 0.0495 0.0598 0.0668 0.0777 0.0960 0.1097 T = 400 degC 35 0.0470 0.0583 0.0710 0.0805 0.0945 0.1158 0.1330 40 0.1963 0.2537 0.3181 0.3855 0.4634 0.5554 0.6488 20 0.0545 0.0664 0.0799 0.0940 0.1093 0.1259 0.1433 dumping height 25 0.0549 0.0700 0.0806 0.0948 0.1105 0.1271 0.1447 (mm) 30 0.0559 0.0691 0.0833 0.0982 0.1153 0.1320 0.1504 T = 600 grdC 35 0.0653 0.0806 0.0978 0.1160 0.1411 0.1577 0.1806 40 0.2590 0.3340 0.4184 0.5117 0.7113 0.7280 0.8496 20 0.0722 0.0874 0.1046 0.1229 0.1423 0.1634 0.1854 dumping height 25 0.0727 0.0881 0.1054 0.1240 0.1436 0.1649 0.1872 (mm) 30 0.0747 0.0907 0.1088 0.1281 0.1486 0.1709 0.1942 T = 800 degC 35 0.0855 0.1048 0.1266 0.1501 0.1751 0.2025 0.2313 40 0.3235 0.4163 0.5206 0.6363 0.7633 0.9034 1.0536 Tab. 1 - Blank page -

Claims (1)

P a t e n t a n s p r ü c h e process for catalytic and adsorbtive Post-cleaning of exhaust gases from diesel engines with a catalytic converter honeycomb coated material, preferably a mixture of LaCoO.3 and other components, d u r c h e k e n n n z e i c h n e t that the exhaust gas successively through a Bulk catalyst with catalytically coated particles for soot adsorption and then is passed through a catalytically coated catalyst honeycomb. 2. Procedure according to claim 1 1 d. G. that the bulk catalyst in an eccentric annulus is located at the foot of the device and the cross-section of the annular space approximately fills. 3. The method according to claims 1 and 2, d. G. that the afterburning and DeNOx device is used as a silencer. 4. The method according to claims 1 to, d. g., as the introduction of the exhaust gas from the engine takes place tangentially and the exhaust gas after 270 degrees after passing it a retaining screen for the bulk catalysts by 90 degrees in the longitudinal direction of the Device and then deflected in 180 degrees to the catalyst honeycomb. 5. The method according to claims 1 to 4, d. G. S that the exhaust gas from the catalytic converter honeycomb is diverted directly through a pipe without passing through a silencer » . Device for carrying out the method consisting of 2 concentrically located Cylinders with tangential feed pipe and in the middle of the inner cylinder Drainage pipe, d. g.q that there is a solid bulk in the annulus, which is delimited by a retaining device and the internal cylinder the hatalysatorwabe carries. 7. Apparatus according to claim 6 S d. g., because the outer cylinder and the Catalyst honeycomb are isolated on the outside or inside. 8. Apparatus according to claim 6, d.g. that the tangential introduction port is arranged centrally to the annular chamber and the upper part of the annular chamber is gas-tight is sealed off from the inlet nozzle in such a way that the exhaust gas passes through the catalyst bed must flow.